句型转换。
How many units must we learn this term?(改为被动语态)
How many units  _______  _______ _______ by us this term?
It took him two hours to do his homework.(改为同义句)
He________ two hours in _________  his homework.
Parents should allow children to choose their own clothes.(改为被动语态)
Children ______ _______ ________  to choose their own clothes.
I was asked to clean the room by my mother.(改为主动语态)
My mother ________  ________  to clean the room.
I believe that Lucy is allowed to have her long hair cut.(改为否定句)
I _________ believe that Lucy  ________ _________ to have her long hair cut.